Compressor and overload protecting apparatus

ABSTRACT

A compressor includes a suction unit for sucking fluid, a compression unit for compressing the fluid sucked through the suction unit, a discharge unit for discharging the fluid compressed in the compression unit, an electric mechanism unit connected to the compression unit and driving the compression unit, and an overload protecting apparatus installed at the discharge unit and stopping operation of the electric mechanism unit if a temperature of the fluid discharged through the discharge unit is higher than a pre-set temperature.

TECHNICAL FIELD

The present invention relates to a compressor and, more particularly, toan overload protecting therefore of a compressor for preventing anoverload to a compressor.

BACKGROUND ART

A compressor, a device for sucking fluid and increasing pressure, iswidely used for an air-conditioner, refrigerator, or the like. There aremany kinds of compressors according to a driving method, including areciprocating compressor, a scroll compressor and a turbo compressor,etc.

The compressor consists of a compression mechanism unit for performingcompression of the fluid and a driving unit for driving the compressionmechanism unit. The driving unit commonly uses a motor convertingelectric energy to kinetic energy.

An overload protecting apparatus for sensing heat generated from a rotorand a stator is installed near the motor. If an overheat is generated,the overload protecting apparatus stops driving of the motor so that themotor may not be damaged from the overload.

However, as for the overheating of the compressor, generally, the motormay be overloaded, and in addition, if the temperature of the dischargedfluid is too high due to an abnormal operation, carbonization of oil,damage of parts and an unstable operation would cause degradation of areliability of the compressor.

DISCLOSURE OF THE INVENTION

Therefore, an object of the present invention is to provide a compressorhaving an overload protecting apparatus that is capable of stoppingoperation of a motor not only when the motor is overheated but also whena temperature of a discharge fluid is too high due to an abnormaloperation.

In order to achieve the above objects, there is provided a compressorincluding: a suction unit for sucking fluid; a compression unit forcompressing the fluid sucked through the suction unit; a discharge unitfor discharging the fluid compressed in the compression unit; anelectric mechanism unit for driving the compression unit connected tothe compression unit; and an overload preventing unit installed at thedischarge unit for stopping operation of the electric mechanism unit ifa temperature of the fluid discharged through the discharge unit ishigher than a pre-set temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of a compressor in accordancewith the present invention;

FIG. 2 is a partial detailed view showing a construction of an overloadpreventing unit of FIG. 1; and

FIGS. 3A and 3B show operation of the compressor in accordance with thepresent invention.

MODE FOR CARRYING OUT THE PREFERRED EMBODIMENTS

The present invention will now be described with reference toaccompanying drawings.

A compressor of the present invention includes: a suction unit forsucking fluid; a compression unit for compressing the fluid suckedthrough the suction unit; a discharge unit for discharging the fluidcompressed in the compression unit; an electric mechanism unit fordriving the compression unit connected to the compression unit; and anoverload preventing unit installed at the discharge unit for stoppingoperation of the electric mechanism unit if a temperature of the fluiddischarged through the discharge unit is higher than a pre-settemperature.

The compressor in accordance with the present invention can be anycompressor regardless of kinds of compressors such as a piston typecompressor, a scroll compressor, a turbo compressor, a so-called Z-typecompressor and a reciprocating (linear) compressor.

As shown in FIG. 1, the scroll compressor includes: a casing 10 having asealed space therein; a compression unit 20 installed inside the casingfor compressing fluid; an electric mechanism unit 50 for providingdriving force to the compression unit 20; and a lubrication unit 60 forallowing the electric mechanism unit 50 and the compression unit 20 tosmoothly operate.

At one side of the casing 10, a suction pipe 11 for sucking fluid fromoutside and a discharge pipe 12 for discharging the compressed fluid areinstalled.

The compression unit 20 includes a fixed scroll 21 having a dischargepassage 23 for discharging compressed fluid at the central portion witha fixed scroll wrap 22 in an involute shape and being fixedly mountedinside the casing 10; and an orbiting scroll 25 having an orbitingscroll wrap 26 in a involute shape corresponding to the fixed scrollwrap 22 and being mounted to form four compression spaces P2 in acrescent space as the fixed scroll wrap 22 and the orbiting scroll wrap26 are engaged with an angular difference of 180°.

A high/low pressure separating plate 24 is installed at an upper side ofthe fixed scroll 21 to section the inner space of the casing 10 into ahigh pressure side P3 and a low pressure side P1 and form a dischargeside muffler at an upper side of the discharge passage 23.

A check valve 40 is mounted at an upper side of the discharge passage 23to prevent the fluid from flowing backward and introduction of thecompressed fluid at the high pressure side P3 into the compression spaceP2.

The electric mechanism unit 50 includes: a stator 51 fixed inside thecasing 10, a rotor 52 for converting electric force to a rotating forcein the stator 51, a rotational shaft 53 for transmitting the rotatingforce of the rotor 52 to the orbiting scroll 25, an Oldham ring 56mounted between the rotational shaft 53 and the orbiting scroll 25 inorder to change the rotational motion of the rotational shaft 53 to anorbiting motion; and a main frame 54 and a lower frame 55 fixedlyinstalled inside the casing 10 in which the rotational shaft 53 isfixed.

The lubrication unit 60 is formed in the rotational shaft 53 andsupplies oil 61 filled at the lower portion of the casing 10 to africtional part inside the casing 10.

The overload protecting device 72 is fixedly installed at the side ofthe discharge passage 23. As shown in FIG. 1, to facilitate installationof the overload protecting device, a fixing recess 71 is formed at thehigh/low pressure separating plate 24 and the overload protecting device72 is installed in the fixing recess 71.

With reference to FIGS. 1 and 2, the overload protecting device 72 isconnected to a winding coil 51 a of the electric mechanism unit 50 andsenses a temperature of a compressed fluid being discharged to thedischarge passage 23. If the sensed temperature is higher than a pre-setvalue, the connection of the winding coil is cut off to stop operationof the electric mechanism unit 50. Then, the operation of the compressoris stopped, and accordingly, the electric mechanism unit 50 and thecompressor are protected. In order to prevent flowing electricity toother members, an insulation member 73 is preferably installed insidethe fixing recess 71.

In particular, as shown in FIG. 2, the overload protecting device 72includes a bimetal switching element 72 a installed at the muffler and aterminal element 72 b for connecting between the motor and the bimetalswitching element 72 a. The bimetal switching element 72 a may beconnected to the winding coil 51 a and the connection may be cut off ata pre-set temperature. At this time, by using the effect thattemperature goes up according to a value of a flowing current, if theflowing current is above a pre-set value, the bimetal switching element72 a stops operation of the electric mechanism unit 50 to protect theelectric mechanism unit 50.

In addition to the overload protecting apparatus 72, in order to preventa damage of the electric mechanism unit 50 due to a high heat near theelectric mechanism unit 50, a second overload protecting apparatus 57may be installed at an upper side of the stator 51 in order to measure aheat generated by the stator 51 and the rotor 52 and stop operation ofthe electric mechanism unit 50 in occurrence of overheat.

In the scroll compressor constructed as described above, the compressionspace (P2) is formed by the fixed scroll 21 and the orbiting scroll 25respectively having the involute shaped fixed scroll wrap 22 andorbiting scroll wrap 26. The fixed scroll 21 is fixed and the orbitingscroll 25 makes an orbiting motion along a circle with a certain radiusin a state that it is fixed not to be rotated, in order to continuouslycompress the fluid.

As compression proceeds, the check valve 40 opens the discharge passage23 due to a pressure difference, the compressed fluid flows to the highpressure side P3 through the discharge passage 23, the compressed fluidof the high pressure side P3 is discharged to outside the casing 10through the discharge pipe 12.

At this time, the overload protecting device 72 is connected to thewinding coil 51 a wound at the stator 51, and if a temperature of thecompressed fluid at the high pressure side P3 is below a pre-settemperature, the overload protecting device 72 mounted at the fixingrecess 71 of the high/low pressure separating plate 24 is maintained atthe connection state as shown in FIG. 3A. Meanwhile, if the compressedfluid has a temperature higher than the pre-set temperature, the windingcoil 51 a is disconnected to prevent an overload of the electricmechanism unit 50, as shown in FIG. 3B.

Besides, if the current flow along the winding coil 51 a of the electricmechanism unit 50 is above the pre-set value, the winding coil 51 a isdisconnected owing to the heat generated according to the current flow,thereby preventing an overload.

In this manner, the overload protecting apparatus for a compressor hassuch a structure that the temperature of the fluid discharged to thehigh pressure side P3 after being compressed in the compression unit isdetected for preventing an overload, so that it can cope with anoverheat of the compressor due to an abnormal operation.

Especially, in the scroll compressor having the high/low pressureseparating plate separating into the high pressure side P3 and the lowpressure side P1, if the overload protecting apparatus is installed inthe vicinity of the electric mechanism unit as in the conventional art,it is not possible to detect an excessive increase in the temperature ofa discharged fluid due to an abnormal operation, failing to quickly copewith the overheat of the compressor. But in the case of the scrollcompressor having the high/low pressure separating plate separating intothe high pressure side P3 and the low pressure side P1 in accordancewith the present invention, an excessive increase in the temperature ofthe discharged fluid due to an abnormal operation can be detected, sothat it can quickly cope with the overheat of the compressor.

INDUSTRIAL APPLICABILITY

As so far described, the compressor of the present invention has manyadvantages.

That is, for example, first, if fluid is compressed in an overheatedstate due to an overheat of a motor, etc., the discharged fluid has anexcessively high temperature. Then, by stopping the operation of thecompressor, the compressor can be prevented from breaking down.

In addition, if the temperature of the discharged fluid after beingcompressed increases due to an abnormal operation, the compressor isstopped from operating, so that oil carbonization of oil or damage toparts according to melting can be prevented.

Moreover, temperature increase of the fluid discharged after beingcompressed due to an over-compression in or leakage from the compressionunit can be prevented.

Furthermore, the compressor can quickly cope with an overheat or anover-compression inside the casing, so that leakage of the fluid isprevented and thus a reliability can be improved.

1. A compressor comprising: a suction unit for sucking fluid; acompression unit for compressing the fluid sucked through the suctionunit; a discharge unit for discharging the fluid compressed in thecompression unit; an electric mechanism unit connected to thecompression unit for driving the compression unit; an overloadprotecting apparatus including a bimetal switching element installed atthe discharge unit and a terminal element for connecting between a motorand the bimetal switching element, the bimetal switching element forstopping operation of the electric mechanism unit if a temperature ofthe fluid discharged through the discharge unit is higher than a pre-settemperature, and for stopping operation of the electric mechanism unitif a current flow through the bimetal switching element is higher than apre-set value; and a casing for receiving the compression unit and themotor, wherein a muffler for preventing noise is housed inside thecasing and has a top wall separated from the top of the casing at thedischarge unit, and a fixing recess is formed in the muffler to receivethe overload protecting apparatus therein, wherein the bimetal switchingelement is received in the fixing recess, and wherein the fixing recesshas a certain depth from an upper surface of the muffler to completelyreceive the overload protecting apparatus.
 2. The compressor of claim 1,wherein said compression unit including a high/low pressure separatingplate installed in the casing and sectioning a high pressure side and alow pressure side, a fixed scroll coupled to the high/low pressureseparating plate and fixedly installed in the casing, and an orbitingscroll for forming a plurality of compression chambers by overlappingwith the fixed scroll and making an orbiting motion by being connectedto the electric mechanism unit.
 3. The compressor of claim 1, whereinthe overload protecting apparatus is connected to a winding coil of theelectric mechanism unit so that if a current flow in the winding coil isabove a pre-set value, the overload protecting apparatus stops operationof the electric mechanism unit.
 4. The compressor of claim 1, furthercomprising: an insulation member for an insulation with the mufflerinstalled at the inner side of the fixing recess.
 5. The compressor ofclaim 1, wherein the liquid enters the muffler through a first openingand exits the muffler through a second opening into a chamber in thecasing, the chamber having a discharge pipe for discharging the liquidfrom the compressor.
 6. A compressor comprising: a suction unit forsucking fluid; a compression unit for compressing the fluid suckedthrough the suction unit; a discharge unit for discharging the fluidcompressed in the compression unit; an electric mechanism unit connectedto the compression unit for driving the compression unit; an overloadprotecting apparatus including a bimetal switching element installed atthe discharge unit and a terminal element for connecting between a motorand the bimetal switching element, the bimetal switching element forstopping operation of the electric mechanism unit if a temperature ofthe fluid discharged through the discharge unit is higher than a pre-settemperature, and for stopping operation of the electric mechanism unitif a current flow through the bimetal switching element is higher than apre-set value; and a casing for receiving the compression unit and themotor, wherein a muffler for preventing noise is housed inside thecasing and has a top wall separated from the top of the casing at thedischarge unit, and a fixing recess is formed in the muffler to receivethe overload protecting apparatus therein, wherein an insulation memberfor insulating the overload protecting apparatus and the muffler fromeach other is installed at an inner side of the fixing recess, whereinthe bimetal switching element is received in the fixing recess, andwherein the fixing recess has a certain depth from an upper surface ofthe muffler to completely receive the overload protecting apparatus. 7.The compressor of claim 6, wherein said compression unit including ahigh/low pressure separating plate installed in the casing andsectioning a high pressure side and a low pressure side, a fixed scrollcoupled to the high/low pressure separating plate and fixedly installedin the casing, and an orbiting scroll for forming a plurality ofcompression chambers by overlapping with the fixed scroll and making anorbiting motion by being connected to the electric mechanism unit. 8.The compressor of claim 6, wherein the overload protecting apparatus isconnected to a winding coil of the electric mechanism unit so that if acurrent flow in the winding coil is above a pre-set value, the overloadprotecting apparatus stops operation of the electric mechanism unit. 9.The compressor of claim 6, wherein the liquid enters the muffler througha first opening and exits the muffler through a second opening into achamber in the casing, the chamber having a discharge pipe fordischarging the liquid from the compressor.